Historical retrospective · Bitcoin
BIP 68 introduced relative sequence-based time locks
BIP 68 gives transaction input sequence numbers a relative-locktime meaning, measured from the confirmation of the referenced output.
Relative timing conditions let a transaction express “wait this long after the earlier output” rather than rely only on an absolute calendar threshold.
That capability supports safer multi-step protocols and helped standardize tools used in later channel and contract designs.
Time-lock semantics are subtle; wallet and protocol authors must account for block-based versus time-based interpretation.
Primary source
This retrospective summarizes the source below in original language and links to the primary record used for the briefing. This is not investment, legal or security advice.